[Java.Base] Update reference API (#1167)

Context: f998c42
Context: 1adb796

Commit 1adb796 added bindings for `java.util.function`.

Commit f998c42 added `[JniConstructorSignature]` to bound
constructors.

Update `src/Java.Base-ref.cs` to contain these changes, so that
`git diff` doesn't constantly show this file as having changed.

Author: jonpryor